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Building Piilley Pattern.                        51

reasons which have been previously mentioned, and so, patterns
of the larger kind at least, are made of layers well glued together.
Fig. 63 represents the making of the pattern for the pulley shewn
in Fig. 10. The rim is first built on the face plate of the lathe in
the following manner :—

Pieces of wood of the form shewn at A being sawn to shape,
are truly planed on one side at least, and also at the ends, by the
help of a shooting board B, which is used as a guide; they are
then fitted together to form the first layers of the rim, by glueing
to the face plate, taking care to put a strip of paper between, which
is always done when work is to be afterwards removed.

When dry, this layer is turned to a true plane, and another
superposed in a similar manner, but so as to 'break joint/ and so
on; the whole is lastly turned on the face E, and, being carefully
removed, is reversed, and again turned on the back side. So
much for the rim. The plate of the wheel is next formed, as at c,
by halving one plank over another at right angles, these being
grooved to receive the filling quarters a a ; the plate is next bored
at the centre to receive the boss, and turned on the outside (see D).
A rabbet having been formed in the rim to receive the plate, one
half of the pattern is complete.

Fig. 64 shews the halving for a pulley, of six arms, each batten
being cut to a fraction of its depth indicated by the figures; and
Fig. 65 shows the method used for five arms, the boss being re-
quired for fastening purposes. These are for the arms themselves.

The upright ribs, used to strengthen such arms (see Fig. 12),
would be halved on their narrow edges, and the boss filled in by
segments as at E, Fig. 65.

Pipes.—Patterns for small pipes are made out of the solid,
but those of a large size are built up as in Fig. 65a. Polygonal
half discs are placed at either end, and at intervals. Upon these
are carefully fastened with glue (and screws if necessary) the pieces
forming the rim. The two surfaces A and B being made true
planes, the half pipes are glued together with paper between," and,
having dogs driven in at the ends c, are centred in the lathe,
Fig. 59. If flanges are needed the ends would be turned as in
Fig. 66, and the flanges fitted in the manner shewn.

Bent pipes cannot be built in this way,  on account of the